Tissue Retractor

ABSTRACT

A tissue retractor device for retracting tissue is disclosed. The device includes a base connected to a plurality of blades distributed around the base. Each of the blades is outwardly movable from the base. A pusher is engaged to the base. The pusher is movable in a longitudinal direction to move the blades to angularly displace each of the blades from a respective closed position to an open position. At least one biasing device is engaged with the base that biases the respective ones of the blades toward a closed position. The closed position is where the blades are relatively close together with respect to the open position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.13/657,516 filed on Oct. 22, 2012, titled “Tissue Retractor” to Alan G.Ellman, all of which is incorporated herein by reference.

FIELD

This present application relates to a surgical tissue retractor.

BACKGROUND

The present invention relates to a device and method for expanding anenclosure such as tissue to expose the operative field in a patient.Entering an operative field such as in connection with specialized backsurgery on or in-between vertebrae of the spine and on spinal discsinvolves various meticulous surgical procedures which can be challengingeven for experienced surgeons who specialize in this particular surgery.Minimally invasive techniques are preferred over traditional opensurgical procedures which require extensive operating time andpost-operative recovery time.

When employing such minimally invasive surgical techniques, one of thechallenging requirements relates to safe retraction of patient tissue inthe target area or operative field to provide sufficient space forimplementation of these techniques. For example, nerve roots areplentiful in this operative field and extreme care must be exercised bythe surgeon to avoid accidentally damaging or even severing any of theseroots when retracting tissue in this operative field. An example of atissue retractor which does not include improvements, advancements andadvantages of the present invention is provided in U.S. Pat. No.7,374,534 issued on May 20, 2008 to Dalton, which is incorporated hereinby reference in its entirety. The present invention provides an improvedretractor device which improves chances of avoiding undesired resultsand thereby greatly improves chances of achieving a successful patientoutcome. Furthermore, the present invention provides greater control,precision, ease of use and may have utility in surgical proceduresperformed in operative fields other than those discussed herein. Otheradvantages and features will become apparent from the description of theinvention.

SUMMARY

In summary, an embodiment of relates to a tissue retractor device and/orto a method for performing a surgical procedure using that device on apatient by a surgeon. The device includes a base hinged to a number ofblades circumferentially distributed around the base. In one embodiment,each of the blades is spring-biased so that the blades close uponthemselves in the default state. Each of the blades is rotatablerelative to its respective hinge when utilizing the retractor deviceunder the control of the surgeon. In one embodiment, one of the bladesis longer than all of the other blades, thereby providing anadvantageously-smaller device-tip configuration by which the surgeon canbetter control such longer blade to maneuver around, and between, nerveroots and other critical elements lying in its path after the device hasbeen surgically inserted into the patient.

In one aspect, the device further includes a pusher mechanism which isthreadably and concentrically connected within the base. Again, afterthe device has been surgically inserted into the patient, the pusherinteracts with the blades in a manner to controllably and angularlydisplace each of the blades from its respective closed position aboutits respective hinge, responsive to the surgeon's manually-rotating thepusher in the threaded connection relative to the base.

To facilitate the surgical insertion or implantation of the device, thedevice further includes a dilator mechanism thread-ably andconcentrically connected within the pusher. The dilator, in oneembodiment, includes a concentrically located shaft having a tip at theend of the shaft which protrudes beyond the end of the largest oneblade. The dilator tip is suitable for penetrating or pushing into thebody of the patient while each of the blades is in its respective closedposition and before the surgeon operates the pusher to displace theblades. And, the tip is particularly suitable for maneuvering betweenadjacent vertebrae in the spine of the patient if back surgery is beingperformed. However, it will be understood that the present embodimentmay be used in broader surgical procedures beyond spinal surgeryincluding OB/GYN, or even non-surgical procedures where one desires toexpand a particular area.

In another embodiment, a method relates to first inserting a guide-wireinto the spinal area of a patient to a desired depth. Then theabove-described tissue retracting device including the dilator having atip protruding beyond any other structure of that device is slid overthe guide-wire. The device is inserted into the patient to a desireddepth, the surgeon maneuvering the tip between target vertebrae, themaneuvering including clockwise and counter clockwise rotation of thedevice while the blades remain closed. Under certain circumstances, theguide-wire may be removed from the patient, either prior to,concurrently with, or subsequent to the dilator tip maneuvering.However, if the guide-wire was not previously removed, after the dilatortip is properly positioned (wherefore ends of the blades are properlypositioned), the dilator and the guide-wire are both removed togetherfrom the device, leaving an inserted portion of the remainder of thedevice including at least a portion of its blades in the patient. Thenon-inserted portion includes the accessible circularly-shaped basenoted above, hinged to the inserted blades, where one of the blades islonger than the other two equally-sized blades. The surgeon maneuversthe one blade beyond and around nerve roots that are in the vicinity ofthe target vertebrae, thereby safely clearing a pathway between andamongst those nerve roots which otherwise obstruct the surgeon'sperformance. The surgeon then operates the pusher mechanism by rotatingits knob relative to the base and controllably displaces each of theblades from its respective closed position to cause tissue of thepatient's body to be retracted. This provides space at the location ofthe operative field for surgical activity. Finally, the surgeon insertsa surgical tool, perhaps inserting one of several tools in sequence,into the device when the device's blades are displaced, and uses eachsuch tool to perform the necessary surgery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of an exemplary embodiment of a retractordevice including its dilator, configured for insertion into a patient;

FIG. 2 is an end view of the configuration of FIG. 1;

FIG. 3 is a perspective view of the embodiment of FIG. 1;

FIG. 4 is a cross-sectional view of the embodiment of FIG. 1, sliced byvertical plane 4-4;

FIG. 5 is a top plan view of the exemplary embodiment of FIG. 1 afterthe dilator has been removed;

FIG. 6 is an end view of the configuration of FIG. 5, being the same endview as that of FIG. 2 but with the dilator removed;

FIG. 7 is the same perspective view as that presented in FIG. 3, butwith the dilator removed;

FIG. 8 is a cross-sectional view of the embodiment of FIG. 5, sliced byvertical plane 8-8;

FIG. 9 is a top plan view of the exemplary embodiment of FIG. 5, afterthe blades have been outwardly displaced or spread apart;

FIG. 10 is an end view of the configuration of FIG. 9, being the sameend view as that of FIG. 6 but with the blades spread apart;

FIG. 11 is the same perspective view as that presented in FIG. 7, butwith the blades outwardly displaced;

FIG. 12 is a cross-sectional view of the embodiment of FIG. 9, sliced bythe vertical plane 12-12;

FIG. 13 is a top plan view of the exemplary embodiment of FIG. 9, butafter a surgical tool had been inserted into the embodiment;

FIG. 14 is an end view of the configuration of FIG. 13, being the sameend view as that of FIG. 10 but with the surgical tool in place;

FIG. 15 is the same perspective view as that presented in FIG. 11, butwith the surgical tool in place;

FIG. 16 is a cross-sectional view of the embodiment of FIG. 13, slicedby the vertical plane 16-16;

FIG. 17 is another perspective view, similar to, but axially rotatedfrom, that of FIG. 7, to more clearly show that one blade is longer thanthe other blades, and more clearly show the base finger-tab or handlepermanently aligned with the longer blade;

FIG. 18 is an exploded view of the embodiment of FIG. 17, but axiallyrotated therefrom to more clearly show certain detailed mechanicalfeatures of the embodiment;

FIG. 19 is a perspective view of the pusher mechanism shown in crosssection in FIGS. 4, 8, 12 and 16;

FIG. 20 is a side view of the pusher mechanism depicted in FIG. 19;

FIG. 21 is an exploded view similar to that of FIG. 18, but also showingthe dilator depicted in cross section in FIG. 4; and

FIG. 22 is a perspective view of an alternative embodiment of theretractor device.

DETAILED DESCRIPTION

In this description, the same reference numeral in different Figs.refers to the same entity. Otherwise, reference numerals of each Fig.start with the same number as the number of that Fig. For example, FIG.3 has numerals in the “30” category and FIG. 4 has numerals in the “40”category, etc.

FIG. 1 is a top plan view of tissue retractor device 10 according to oneembodiment of the present invention. Retractor device 10 may beconstructed from stainless steel and/or hard or elastic or plasticand/or other materials suitable for use as, or within, a surgicallyinvasive tool for use in surgical procedures upon a human body.Alternatively, retractor 10 may be constructed from a material that iscompatible with a visualization system, e.g., a fluoroscope or amagnetic resonance imaging (MRI) machine, where the tip of its longestblade (discussed below) is radio opaque to allow the user to visualize,in real time as the surgery is progressing, exactly where the end ofthat device blade is located in the body of the patient.

Base 11 can be a circular structure and includes screw-threads formedtherein (threads 180 in FIG. 18) for thread-ably engaging threads 18which are formed on the outside of pusher mechanism 14. (Base 11includes certain structure which is analogous to a nut having threadsformed therein which can receive threads of a compatibly-mated bolt, thelatter being analogous to a portion of the pusher.). Of course, base 11may be any other configuration depending on the desired result such assquare or shaped to interconnect with a wrench or other suitable tool.

In the present embodiment, three retractor blades 12 are spacedcircumferentially around base 11. Each blade 12 includes extendedportion 12 a and hinge portion 12 b, wherein each blade 12 is hinged bya respective hinge-pin 13 (located in hinge portion 12 b, to base 11.One skilled in the art, however, will understand that any number ofblades 12 may be employed. In one embodiment, blades 12 arespring-biased toward a closed position, as shown, by springs 19. Eachblade has its own spring 19 associated with its respective hinge pin,and discussed in further detail below. Although the use of independentcoil springs are shown in the respective figures, one skilled in the artwill readily understand that alternative spring means may be employed.For example, elastic membranes or materials (rubber for example) may beused in place of the springs. In one embodiment, an elastic washer(e.g., an O-ring) is circumferentially disposed, encircling areasbetween base 11 and hinge portion 12 b of all three hinge portions 12.Thus, when any of the blades is moved into an open or retractedposition, the washer provides elastic force in response thereby biasingthe blades 12 toward their closed position. The use of a singular O-ringmay have advantages in manufacturing costs or assembly. In anotheralternative embodiment, the blades 12 may be molded together with base11 with a plastic material where the blades are biased inward based onthe elasticity of the plastic material used.

Pusher mechanism 14 is threadably engaged to base 11 for movement in andout thereof. The Pusher mechanism 14 is manually rotatable by graspingby a user (e.g., a surgeon, aid, or device) and turning knob finger tabs15. In an alternative embodiment, the dilator mechanism (including knob16) may be welded to pusher mechanism 15. Operation of the entireretractor device including the pusher mechanism shall be discussedbelow.

Dilator mechanism knurled knob 16 (hereinafter knob 16) is threadablyengaged with pusher mechanism 15, similar to the thread-able engagementbetween pusher 15 and base 11, and is shown in FIG. 1 in itstightened-down position (completely inserted into pusher mechanism 15).Pusher mechanism threads 190, with which dilator mechanism thread-ablyengages, are shown in perspective FIG. 19. Dilator mechanism knurledknob 16 may be welded, adhered or attached by any other means as well.Dilator mechanism tip 16 t, at the left hand side of FIG. 1, is open atits center (to ride over the guide-wire) and is connected to knob 16 bya hollow dilator tube 42 (See FIG. 4 and FIG. 21). The dilator tube 42and tip 16 t form a completely open interior to accommodate insertion ofa guide-wire (not shown) therethrough. Finger tab 17 is fixedlyconnected to base 11 to provide a protuberance for firm grasping by theuser or other individual using the device. In one embodiment, the fingertab 17 is located at a position on the base 11 in alignment with one ofthe three blades which is longer than the other two blades (not shown inFIG. 1). By noting location of tab 17, the user knows the location ofthe longer blade. The significance and functionality of this longerblade length variation is discussed below. It will be understood,however, that the blades 12 may be all the same length, varying lengthsor any combination therebetween and the present description should notbe construed as limiting. In another embodiment, finger tab 17 may belocated at a specific radial position (164 degrees from some referencepoint for example) to aid in a specific surgical procedure. It will beunderstood that finger tab 17 may be located at any radial positionsuitable for its desired purpose.

FIG. 2 is an end view of retractor device 10 shown in FIG. 1. In thisFig. three finger-tabs 15, 15 a and 15 b are shown spaced evenly aroundand extending from dilator knob 16. Also shown is finger-tab 17 which isfixedly connected to base 11. In operation, after a stab incision ismade by the user and after a guide-wire is inserted into the stabincision to determine appropriate penetration depth, location or otherdesired use of the guide-wire, hollow tip 16 t (FIG. 1) is inserted overthe guide-wire and pushed into the body of the patient. To accomplishthis penetration, the user or other individual using the device may useany of the finger-tabs 15, finger tab 17 and/or knob 16 to provide agood structure for grasping. One will understand that grasping may bedone by either human or mechanical means (for example wrench or roboticdevice). In one embodiment, a rotary motion, clockwise andcounterclockwise of the entire retractor device 10, and other motionscan thus be used to work the retractor device 10 into the patient andinto its needed position to position tip 16 t at the optimum location inthe operative field. The guide-wire (not shown) protrudes from aperture20 and can be withdrawn through aperture 20 when the optimum location isobtained, or before or after that occurrence or with the removal of thedilator itself. During this portion of the operation, blades 12 are inthe closed position as shown in FIG. 1. The tip 16 t may also be used toauto-position the device at the desired location. When used in spinaldisc surgery, the tip 16 t may be auto-located inside the disc at thedesired location such that when the dilator assembly 14, 15, 16 isremoved, the blades 12 are in the correct position to be opened at thedesired location. In one embodiment, this is accomplished throughpositioning the tip 16 t between vertebras.

FIG. 3 is a perspective view of the embodiment of FIG. 1. Blade 12 _(L)is the longer blade noted above and, as depicted, it aligns with fingertab 17 affixed to base 11 (although it may be at any radial position).Longer blade 12 _(L) may be considered a multipurpose blade for useduring a procedure generally providing for retraction of specificanatomy, identification/targeting specific anatomy, sweeping an area tomove away anatomy, and identification of the device within the patient(e.g., under various imaging modalities), as discussed herein.

FIG. 4 is a cross-sectional view of the embodiment of FIG. 1, takenalong the section 4-4. The hinge pin 13 depicted as a black dot is shownaxially and is the hinge pin associated with longer blade 12 _(L) andabout which blade 12 _(L) rotates. Spring 19 is shown seated in arecessed portion of base 11 and presses against shoulder 40 of blade 12_(L), wherefore spring 19 is biased in a manner to keep blade 12 _(L)closed, as shown (such may be the same for remaining blades 12). Asdiscussed above, other biasing means may be used instead of spring 19shown herein. Pusher tube (or expander tube) 41 extends from pusher 14to a distal location between the blades 12. Pusher tube 41 has a distalend 41 a that is set in length from pusher 14 such that when pushermechanism 14 is fully tightened into and bottomed out in base 11, distalend 41 a will either be positioned at or above section 51 of any of theblades 12 or between section 51 for reasons that will be discussed anddepending on the desired operation. In the embodiment shown in FIGS. 1and 4, distal end 41 a is positioned at or above section 51 such that inits tightened position, distal end 41 a does not abut section 51 andtherefore the blades 12 are not expanded. In this configuration, theretractor device 10 is positioned into a patient while the blades 12 arein their contracted position.

FIG. 5 is a top plan view of the embodiment of FIG. 1 according toanother embodiment. In this embodiment, the pusher assembly(collectively pusher 14, pusher tube 41, dilator tube 42 and knob 16) isreplaced with a second pusher assembly 15. Alternatively, instead of theentire pusher mechanism, the dilator including its knob 16, tube 42 andtip 16 t may be removed leaving the remaining items of the pusherassembly. Blades 12 are still in a closed position. Blades 12 each havethree sections 50, 51 and 52, shown in FIG. 5. Section 50 extendssubstantially uniform in diameter such that pusher tube 41 is positionedalong the interior in a non-interfering way between blades 12. Section51 has a tapered configuration to abut against distal end 41 a as willbe discussed. Section 52 forms an extended tapered configuration withblades 12 as needed for working the device 10 into the operative area.The relationship between cylindrical configuration 50 and conicconfiguration 51, both configurations formed by the three blades whilein a closed position, is responsible for spreading the blades, and isdiscussed in detail below. However, one skilled in the art willunderstand that the tube 42 may interact with blades 12 through anyother means known in the art to expand the blades 12. For example, tube12 could include gear teeth that mate with teeth on blades 12 to causegear like rotation of blades 12 about the hinge.

FIG. 6 is an end view of the configuration of FIG. 5. Two blades 12 andone blade 12 _(L) are visible in the center of the Figure. Light posts60 are attachments for light fibers or light cables (not shown) used forilluminating the surgical site. The light posts also serve as detentsfor control of surgical instruments (not shown in this Fig.) used withthe configuration of FIG. 5, to be discussed below. FIG. 7 is the sameperspective view as that presented in FIG. 3, but with the dilatorremoved.

FIG. 8 is a cross-sectional view of the embodiment of FIG. 5 taken alongthe section 8-8. Pusher tube 41 is shown to have a length which, whilethe pusher 14 is in a relatively unthreaded and non-bottomed outposition, does not enter section 51 of the blades. As such, springs 13maintain sufficient force onto shoulders 40 to hold blades 12 and 12_(L) in closed positions as shown. The structure through which hinge pin13 is inserted has hard edge 80 which serves as a limit stop to theadvancement of pusher 14 as it is threaded into base 11, operation ofwhich is discussed below.

With reference to FIGS. 8 and 12, the operation of the embodiment isdescribed. In FIG. 8, the pusher 14 is in its unthreaded state. Next,pusher 14 is threaded into base 11 such that distal end 41 engagessection 51. As can be seen in FIG. 12, distal end 41 a abuts section 51and expands blades 12 apart and against the biasing of springs 19. Thepressure against section 51 by distal end 41 a and the counter force bysprings 19 create a degree of rigidity that holds blades 12 in place. Ofcourse, one will understand that springs are not necessary and onlydistal end 41 a against section 51 may be employed. The angle of section51 may be chosen such that an optimum force or speed of retraction maybe achieved. For example, the angle of section 51 may be chosen shallowsuch that more rotation of pusher 14 is required for each degree ofopening for blades 12. This will provide a relatively larger amount oftorque where opening the operative area is difficult and needs moreforce. Likewise, where speed is desired, the angle of section 51 may besteeper such that a greater degree of opening will be achieved with eachrotation of pusher 14. Additionally, the sections 51 of each blade 12may be pitched differently to cause blades 12 to open at different ratesper rotation of pusher 14.

FIG. 9 is a top plan view of the embodiment of FIG. 5 after the bladeshave been outwardly displaced or spread apart. At the left-hand side ofthe drawing, it can be readily seen that the end of blade 12 _(L)extends beyond the ends of blades 12 and that all blades are spreadapart. In FIG. 9, it can be seen that pusher 14 has been screwed orthreaded into base 11 to the maximum extent possible. It will be notedthat the depth of pusher threaded into base 11 or the degree of stopbetween shoulder 40 against base 11 may be set to ensure the blades 12open only a predetermined amount.

FIG. 10 is an end view of the configuration of FIG. 9, being the sameend view as that of FIG. 6 but with the blades in their open andexpanded configuration. Two blades 12 and one blade 12 _(L) are shown,Open space 61 is provided between the blades in FIG. 10 representingvision into the operative area that allows the user or the user toaccess the targeted for surgical intervention. Tabs 15 are shown in thesame position in which they appeared in FIG. 6. For ease ofpresentation; however, it should be understood that after pusher 14 hasbeen screwed into base 11 to the desired distance to achieve the desiredexpansion of the blades 12, as shown, there is no requirement that tabs15 on the pusher maintain the same relative position with respect to tab17 on the base 11, although that may coincidentally occur. FIG. 11 isthe same perspective view as that presented in FIG. 7, but with theblades outwardly displaced, shown at end 110 of blades 12 and 12 _(L).

FIG. 12 is a cross-sectional view of the embodiment of FIG. 9, the viewtaken along the section 12-12. Pusher 14 is shown as coincidentallybeing completely threaded into base 11 while structure of base 11simultaneously abuts limit stop edge 80. However, in one embodiment,limit stop 80 is the primary mechanism to prevent further movement ofpusher tube 41 and corresponding expansion of the blades 12. Further, inanother embodiment, the limit stop 80 is positioned such that it isreached before spring 19 is fully compressed to ensure that no excessivewear or damage results to spring 19. It should be noted that pusher tube41 has necessarily advanced to the left in FIG. 12 and, by thattranslational motion, it is pressing against the inside walls of section51 of the blades. This motion against section 51 causes the blades tospread apart, against counterforce spring resistance from springs 19 asshown by the contact between blade-shoulder 40 and spring 19. The endsof the blades 110 are shown spread apart. The spreading of the blades isconstrained to an outward displacement limit as determined by thetransverse movement limit of pusher tube 41 which, in turn, isdetermined by limit stop 80. In an alternative embodiment, in thestructure containing hinge pin 13 (FIG. 8), the face of that structureopposite to that of limit stop 80 can be extended to the left to furtherreduce motion of shoulder 40 and, if extended sufficiently can be analternative limit stop to that provided by face 80.

Different retractors can be designed for different surgical tasks.Different retractors can have different outward blade displacementlimits as functions of different pusher tube lengths and/or as functionsof different degrees of taper of section 51. Typically, thesedisplacements may be in the two (2) to twelve (12) millimeter range, butis not limited to any particular displacement amount. The more severethe taper of section 51, the greater the blade displacement is obtainedper angle of rotation of pusher tabs 15. With other parameters beingequal, however, a greater taper to section 51 yields a greater effortthan otherwise is required by the user in rotating pusher tabs 15 toachieve that greater blade displacement. Conversely, the less severe thetaper of section 51, the smaller the blade displacement is obtained perangle of rotation of pusher tabs 15 with other parameters being equal.However, with a lesser taper to section 51, a lesser effort thanotherwise is required by the user in rotating pusher tabs 15 to achievethat lesser blade displacement. Different retractors having thesedifferent mechanical advantages requiring greater or lesser effort areadvantageously used in different surgical scenarios. Moreover, theopening distance between blades 12 may be adjustable for variousprocedures. The adjustment may be predetermined based on the dimensionsof the components, or it may be adjustable during a procedure byutilizing pusher tubes 41 of various lengths. In an example, a largeropening retractor device may be used by OB/GYN procedures. Examples ofopening distances may include two millimeters (2 mm) to eighteenmillimeters (18 mm), or more. The opening distances (see ends 110 ofFIGS. 11 and 12) of the blades 12, and the associated size of allcomponents, may be smaller or larger for any given procedure and are notlimited by the exemplary embodiments described herein.

FIG. 13 is a top plan view of the exemplary embodiment of FIG. 9, butafter a surgical tool is inserted into the embodiment. Surgical tool 130is threadably and concentrically connected to pusher 14 similarly to howdilator knob 16 was threadably and concentrically connected to pusher14. Surgical tool 130 is intended to represent a generic tool, and itsend 131 protrudes beyond the ends 110 of blades 12 and 12 _(L). Thedevice 10 can be a conduit used, for example, to allow illumination andviewing if operatively connected to fiber optic light sources (via lightterminals 60 in FIG. 14). Or, device 10 can be used to allow a differentdevice to perform suction, or it could be used to allow otherinstrumentation to occupy the conduit to function as a clipper, acaliper, a pincher, a cauterizer, etc., depending on what is threadablyattached to pusher 14 and what is inserted into the conduit.

FIG. 14 is an end view of the configuration of FIG. 13, being the sameend view as that of FIG. 10, but with the surgical tool in place.Surgical tool 130, regardless of its utility or function, can beconfigured with a plurality of handle-indentations 131 to serve as bothconvenient hand-grips and detents relative to light posts 60. In otherwords, light posts 60, which supply fiber optic light paths to thesurgical sight, also serve as posts which can provide mechanical detentsto hold surgical tool 130 in place, after the user positions it tohis/her liking. FIG. 15 is the same perspective view as that presentedin FIG. 11, but with surgical tool 130 in place, its end 131 showingbeyond the ends 110 of the blades. FIG. 16 is a cross-sectional view ofthe embodiment of FIG. 13, taken along the section 16-16, with tool 130in place.

FIG. 17 is another perspective view of tissue retractor device 10 in aclosed-blade state with it including pusher 14 but not dilator 16 asshown in FIG. 1. Tool 130 cannot be included within the device in thisview, because the device is in a closed-blade state. Longer blade 12_(L) is clearly visible in this view and is aligned with tab 17 on thebase.

FIG. 18 is an exploded view of the embodiment of FIG. 17, but axiallyrotated therefrom to more clearly show certain detailed mechanicalfeatures of the embodiment. Each blade-shoulder 40 is held in place byhinge pin 13 when inserted into apertures 13 a. As can be seen from theFig., each spring 19 pushes against its respective shoulder 40 from theside opposite to the side seen in the Fig., and because of the locationof hinge pin 13 and its apertures 13 a relative to the point of forcefrom spring 19 onto the shoulder, each blade 12 is pressed against theother two blades which are similarly biased. In other words, all threeblades are pressed against each other as a result of the three springspushing, respectively, against the three shoulders. The interiorsurfaces, or a portion of an interior surface, of blades 12, 12 _(L) maybe finished to provide reduced glare from illumination or to provideimproved illumination conditions. The color of the interior surface mayalso be selected to provide improved illumination depending on theprocedure. Examples of finishes may include a flat finish, a mirroredfinish, and/or a colored finish.

FIG. 19 is a perspective view of the pusher mechanism shown in crosssection in FIGS. 4, 8, 12 and 16. Threads 190 are shown which arearranged to receive, concentrically, first the dilator 16 and, afterthat fulfills its purpose and is removed (unscrewed), then surgical tool130.

FIG. 20 is a side view of the pusher mechanism depicted in FIG. 19.Pusher tube or expander tube 41 is cylindrical in shape, and readilyfits within the generally cylindrical shape 50 formed by the threeblades. However, the diameter of cylindrical pusher tube 41 is largerthan radially-taken cross sectional diameters of the three bladesproviding conical shape 51. Therefore, the blades are forced openagainst opposing bias forces of springs 19 when the pusher handle tabs15 are rotated because that causes pusher tube 41 to acquiretranslational motion and advance towards blade ends 110, therebyspreading those blades to allow that translational motion.

FIG. 21 is an exploded view similar that of FIG. 18, but also showingthe dilator depicted in cross section in FIG. 4. Knob 16 is shown, alongwith dilator tube 42 and dilator tip 16 t. Knob 16 screws into pushermechanism 14 which, in turn, screws into base 11.

FIG. 22 is a perspective view of an alternative embodiment 220 of theretractor device. Additional features may include a window 222 throughblade 12 _(L) where a user may access tissue from the side for sampling.The windows may be located, for example, to allow access by biopsydevices placed through pusher tube 41. The windows may also beconfigured to allow tissue to protrude through one or more of blades 12such that inspection and/or sampling of the tissue may be performed(biopsies for example). As shown, window 222 is aligned with the blade12 _(L) that is also aligned with finger tab 17 that provides theposition to the user. Additionally, blades 12 may include a number ofwindows (e.g., openings therethrough) to provide additionalopportunities for tissue inspection, resection, reduce weight and/oralter structural rigidity and strength. Moreover, blades 12 may bepartially or substantially skeletonized.

In operation of the above-described embodiment, referring to all Figurescollectively, the user first makes a stab incision and may insert aguide-wire to determine depth of penetration. Then, if a guide-wire isused, the user inserts the device 10 in FIG. 1, including the dilatormechanism having knob 16, over the guide-wire which enters the dilatormechanism via the hole in tip 16 t. The user grasps base 11 includingtab 17 with one hand and grasps pusher/pusher tabs/knob combination14/15/16 with the other hand and, without rotating pusher 14 relative tobase 11, slides device 10 down the guide-wire and works device 10 intothe body of the patient by clockwise and counterclockwise and othermotion. These tabs offer a secure gripping configuration for the user.All blades 12 and 12 _(L) remain closed during this portion of theprocedure by force of springs 19. If no guide-wire is used, the sameprocedure may be followed without interacting with the guide-wire. Aftertip 16 t is positioned in the correct position, and this can bedetermined by any known means in the art including fluoroscopy or othermeans in combination with a radio opaque tip 16 t or a radio opaque endof blade 12 _(L), dilator assembly and the guide-wire can be removed.Alternatively, the retractor may be auto-located with or without the useof imaging as discussed herein.

Then, with the blades remaining closed, the user, in one embodiment,uses longer blade 12 _(L) to maneuver around nerve roots and/or otherstructure(s) in his/her path (this may be done before or after removalof the guide wire), without damaging nerves or causing an unwantedresult. The longer blade 12 _(L) is advantageous for this purposebecause it offers a small effective tip at the end of device 10 ascompared with an embodiment having same-length legs 12 (e.g.,substantially equal length legs). This smaller tip permits easiermaneuvering around nerve root obstructions and the like which,importantly, supports better patient outcomes. Other embodiments mayinclude retractor devices having two or more blades. In practice, thelonger blade 12 _(L) may be used to sweep an area such that the user tomove aside specific anatomy (e.g., an exiting nerve root). The sweepprocedure may be performed by turning the retractor. Additionally, thelonger blade 12 _(L) may be used to retract or specify certain anatomyor to provide improved targeting during imaging using a radio opaquematerial near the distal end. An example of specifying particularanatomy, the longer blade 12 _(L) may be used to target an exiting nerveroot and controllably retract/push it aside.

Next, the user installs the dilator assembly shown in FIG. 8 thatincludes a longer pusher tube 41. The user rotates tabs 15 relative totab 17 to advance pusher tube 41 into the vicinity of section 51. Therotational motion of tabs 15 and, thus, rotational motion of threads 18,provide translational motion to pusher tube 41 which, in turn, pressesagainst section 51, thereby spreading blades 12 and 12 _(L) againstforce of springs 19. The spreading of these blades pushes patient tissueout of the way so the user can have clear access to the site 61 as shownin FIG. 10, such as vertebrae or discs, upon which surgical proceduresshall be performed. Surgical tools and/or instrumentation are introducedthrough the opening to site 61 which can be held in place by detents incombination with light terminals 60.

In this specification, various preferred embodiments may have beendescribed with reference to the accompanying drawings. It will, however,be evident that various modifications and changes may be made thereto,and additional embodiments may be implemented, without departing fromthe broader scope of the invention as set forth in the claims thatfollow. The present invention is thus not to be interpreted as beinglimited to particular embodiments and the specification and drawings areto be regarded in an illustrative rather than restrictive sense.

It will be appreciated that the system and methods described herein havebroad applications. The foregoing embodiments were chosen and describedin order to illustrate principles of the methods and apparatuses as wellas some practical applications. The preceding description enables othersskilled in the art to utilize methods and apparatuses in variousembodiments and with various modifications as are suited to theparticular use contemplated. In accordance with the provisions of thepatent statutes, the principles and modes of operation of this inventionhave been explained and illustrated in exemplary embodiments.

It is intended that the scope of the present methods and apparatuses bedefined by the following claims. However, it must be understood thatthis invention may be practiced otherwise than is specifically explainedand illustrated without departing from its spirit or scope. It should beunderstood by those skilled in the art that various alternatives to theembodiments described herein may be employed in practicing the claimswithout departing from the spirit and scope as defined in the followingclaims The scope of the invention should be determined, not withreference to the above description, but should instead be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled. It is anticipated andintended that future developments will occur in the arts discussedherein, and that the disclosed systems and methods will be incorporatedinto such future examples. Furthermore, all terms used in the claims areintended to be given their broadest reasonable constructions and theirordinary meanings as understood by those skilled in the art unless anexplicit indication to the contrary is made herein. In particular, useof the singular articles such as “a,” “the,” “said,” etc. should be readto recite one or more of the indicated elements unless a claim recitesan explicit limitation to the contrary. It is intended that thefollowing claims define the scope of the invention and that the methodand apparatus within the scope of these claims and their equivalents becovered thereby. In sum, it should be understood that the invention iscapable of modification and variation and is limited only by thefollowing claims.

1. A tissue retractor device for retracting tissue, said devicecomprising: a base connected to a plurality of blades distributed aroundsaid base, each of said blades being outwardly movable from the base; apusher engaged to said base, said pusher movable in a longitudinaldirection to move said blades to angularly displace each of said bladesfrom a respective closed position to an open position; at least onebiasing device engaged with the base that biases the respective ones ofthe blades toward a closed position, wherein said closed position iswhere said blades are relatively close together with respect to the openposition; wherein each of the blades includes a respective one of aplurality of shoulders, wherein each of the shoulders has a surfaceextending substantially perpendicular and outward from an axis of thebase when the blades are in a closed position, wherein the axis isparallel to a movement direction of the pusher; wherein the baseincludes at least one surface substantially perpendicular to the axis;wherein the biasing device is positioned between the surface of the baseand the surface of the shoulders such that the biasing device iscompressed in a direction substantially parallel to the axis when theblades are moved toward the open position from the closed position. 2.The device of claim 1, wherein the pusher threadably engages said basesuch that rotation of the pusher moves the pusher in said longitudinaldirection.
 3. The device of claim 1, wherein: the biasing device is atleast one elastic device positioned between a portion of the blades andthe base; and the blades compress the elastic device when the bladesmove toward the open position to bias the blades toward the closedposition.
 4. The device of claim 3, wherein the elastic device is aplurality of springs, wherein each of the springs is positioned betweenthe surface of the base and a respective ones of the surfaces of theshoulders to bias the blades toward the closed position.
 5. The deviceof claim 3, wherein: the elastic device comprises an O-ringcircumferentially positioned around a surface of the base; the O-ring ispositioned between the surfaces of the shoulders and the surface of thebase such that movement of the blades toward the open position moves theshoulders against the O-ring to bias the blades toward the closedposition.
 6. The device of claim 4, further comprising: a plurality ofapertures in the base, wherein the at least one surface of the base is aplurality of surfaces at a bottom portion of respective ones of theapertures; wherein each of the springs residing in a respective one ofthe apertures; wherein an axial end of each of the springs abuts arespective ones of the shoulders; wherein movement of the blades towardthe open position compresses each of the springs between the bottomportion of each aperture and respective one of the surfaces of theshoulders to bias each of the blades toward the closed position.
 7. Thedevice of claim 6, wherein a length of each of the springs is sized suchthat each shoulder abuts the base before fully compressing the springwhen the blades are moved toward the open position.
 8. The device ofclaim 6, wherein a length of each of the springs is sized such that eachof the springs fully compresses prior to the shoulders abutting the basewhen the blades are moved toward the open position.
 9. A tissueretractor device for retracting tissue, said device comprising: a baseconnected to a plurality of blades distributed around said base, each ofsaid blades being outwardly movable from the base; a pusher engaged tosaid base, said pusher movable in a longitudinal direction to move saidblades to angularly displace each of said blades from a respectiveclosed position to an open position; at least one biasing device engagedwith the base that biases the respective ones of the blades toward aclosed position, wherein said closed position is where said blades arerelatively close together with respect to the open position; each of theblades is constructed with an elastic material and is the biasingdevice, wherein the material blades biases the blades toward the closedposition 10-17. (canceled)